Gasifier and gasification methods using thereof

ABSTRACT

This invention is related to a gasifier and gasification methods realized in said gasifier to provide modular solutions at geographical areas where the access is difficult by processing the refuse-derived-fuel (RDF) obtained from waste including hazardous, industrial and municipal waste in an environmentally sound manner. Switching between the updraft and downdraft gasification modes in said gasifier is possible without the interruption of the system. Therefore energy, labor and time saving is realized via the invented gasifier and the gasification method.

This invention is related to a gasifier which is used to recover gasfrom waste by thermally processing the waste and is also related togasification methods using this gasifier. Specifically, this inventionis related to gasification methods realized using this gasifier in whichswitching between downdraft and updraft modes can be realized withoutany interruptions according to the feedstock material introduced and thegas recovered, for which the gasification realized under vacuumconditions with high efficiency.

In prior art, downdraft and updraft gasifies were used for wastegasification. Either downdraft gasifiers or updraft gasifiers or eventhe up/downdraft gasifiers are used. However, it is not possible toswitch from one mode to another without shutting down the process.

In prior art, WO2005/047435 discloses an up/downdraft gasifier. Howeverthis reference does not include any disclosure regarding the smoothswitching between the systems without interrupting the process.

In US 2007/169411 a circulating bed up/downdraft gasifier has beendisclosed. However, it is not easy to maintain the inside temperature ata fixed rate with this circulating bed gasifier. Since the reductionreactions will not be regulated, sudden changes in gas output will bevery high.

In WO2007/081296 which belongs to the owner of the present application,it is disclosed that ash and tar production is high in circulating bedup/downdraft gasifies compared to fix bed up/downdraft gasifiers. Duringthe suction of the gas, partially un-processed feedstock will come outalong with and the pyrolytic operation will not be proper. In additionto that, since the unprocessed feedstock will leak from the gasifier,full process may not be realized.

Selection of the downdraft or the updraft operation mode in a gasifierdepends on the feedstock to be introduced and type, the quality of theoutput gas. This present gasifier provides smooth switching betweenmodes without interrupting the process.

OBJECTS OF THE INVENTION

One of the objects of this invention is to provide modular solutionsinstead of huge plants at geographical areas where the access isdifficult by processing in an environmentally sound manner therefuse-derived-fuel (RDF) obtained from waste including hazardous,industrial and municipal waste.

Another object of this invention is to let the smooth transfer betweenmodes without interrupting the process. Therefore energy, labor and timesaving is realized via the invented gasifier and the gasificationmethod.

Another object of this invention is to obtain a gasifier and agasification method which decreases pollution in the output gas andincreases the hydrogen content.

Another object of this invention is to obtain a gasifier and agasification method which prevent the solidification of feedstock andclinker formation within the reactor and provides continuous gasproduction.

Below is the detailed description of this gasifier and the gasificationmethod in order to reach the objects. Particular technical terminologyused in text is explained herebelow.

Gasification: It is the chemical transformation of organic solid andliquid waste in syngas in an environment at 800-1200° C. with partialoxidation.

Incineration: It is the combusting process of municipal solid waste at atemperature of 1200-1600° C. within full oxygen environment. Some of thedifferences between gasification and incineration are:

in incineration hydrogen and oxygen combine and form vapour whereas ingasification the vapour is cracked in this 2 molecules.

CO2 is to be formed in incineration, whereas CO in gasification

a) The incineration process mainly forms carbon monoxide and vapor.These are waste gases and are let into the atmosphere. However, thesyngas formed in gasification process is mainly formed of hydrogen andcarbon monoxide gases. The syngas is not a waste gas. This can be usedin burners, in gas turbines or in internal combustion engines forelectrical energy production.

b) Incineration forms complex molecules containing poisonous materialssuch as dioxins and furans. Whereas gasification transforms complexmolecules into gases with simpler molecule formation and prevents theformation of poisonous compounds such as dioxins and furans.

Pyrolysis: It is the thermal degradation of solid waste at 500-600° C.and in no oxygen containing environment. The syngas formed mainlycontains hydrogen, carbon monoxide, carbon dioxide, methane and tarincluding complex hydrocarbons. This gas mixture can be used in burnersfor burning purposes, in gas turbines and internal combustion enginesfor electrical energy generation or coal and active carbon production.

The invention will be described herebelow with reference to the attacheddrawings in which

FIG. 1 is the general outlook of the plant in which the gasifier andgasification method according to this invention are used

FIG. 2 shows the schematic cross section of the gasifier working inupdraft mode.

FIG. 3 shows the schematic cross section of the gasifier working indowndraft mode.

FIG. 4 shows the schematic cross section of the ash pool of thisinvention.

DETAILED DESCRIPTION OF THE INVENTION

A gasifier (1) and gasification methods have been developed in order toreach the objects as mentioned above and to eliminate disadvantages ofthe prior art. With reference to FIG. 1,

the present gasifier (1) comprises a scale (9.2),

A bottleneck zone (2) that comprises a double sliding valve (9) and arotating valve (9.1) where the waste is exposed to heat for the firsttime in oxygen free environment;

A drying zone (3.1) located under the bottleneck zone (2) with adiameter bigger than the bottleneck zone comprising a higher syngasoutlet zone (3.2), a safety valve (11), a level indicator (12), aninspection glass (12.1), a sliding cover (12.2), a thermocouple (13.2),a pressure forwarder (14), a pressure meter in syngas outlet zone, aproportional valve (19) and a hydraulic piston (21);

a pyrolysis zone (4) located under the drying zone (3) comprising apreheated air and oxygen inlet (4.1), air nozzles (4.4), a vibrator(10), a thermocouple (13.1), liquid hazardous waste injection nozzles(20), a proportional valve for hazardous liquid waste (20.1);

a cambered oxidation zone (5) comprising top air nozzles (4.2), bottomair nozzles (4.3), an air chamber (4.7), a bottom syngas outlet zone(6.1), proportional valve for air and oxygen inlet (6.3), igniters (8),a temperature meter in first oxidation zone (13), a pressure meter(14.1) at the syngas outlet zone;

a reduction zone (6) interior surface of which is covered withrefractory material to prevent heat dissolvement comprising upper airnozzles (4.5), lower air nozzles (4.6), an air chamber (4.8), lowerpreheated air or oxygen inlet (6.2), proportional valve (6.4) for air oroxygen inlet, an ash grate (7.1) at the gas outlet zone for creatingcentrifugal effect, vapour nozzles (7.2) for increasing the carbonmonoxide and hydrogen amount to enrich syngas, an igniter (8.1),igniting system (10.1) for the arc formation, a thermocouple (13.3), avapour proportional valve (15) for regulating the vapour percentage;

an ash section (7) comprising ash discharger (7.3), an ash pool (22), afirst threaded carrier (22.1) to convey big particles from ashdischarger into the ash pool, a second threaded carrier (22.2), an ashcarrying palette (22.3);

a precooler and scrubber system (23) placed between the gasifier reactorand fan and comprising a cyclone, syngas vapor exchanger, a gas cleaningscrubber and an electro static precipitator at least one fan (24); andvalves (17, 18).

The gasifier permits the switching between downdraft and updraft modeswithout any interruption during the gasification process according tothe feedstock material and the gas produced.

The gasifier (1) contains the an ash section (7) and at least one ashdischarger in order to create centrifugal effect, at least one ash pool(22), at least one first threaded carrier (22.1) which conveys bigparticles coming from ash discharger into ash pool, at least one secondthreaded carrier (22.2), at least one ash carriage palette (22.3), atleast one dry ash pool (22.4). The second carrier (22.2), axiallyrotates and carries small particles of ash accumulated at the bottom andpopped to the surface through the ash carrying palette (22.3) into thedry ash pool (22.4).

The double sliding valve (9) located at the bottleneck zone prevents theleakage and moves horizontally back and forth reciprocally. It is formedof two valves located as one on top of the other one and which is drivenby a hydraulic piston.

When the sliding valve (9.1) is open the RDF weighted on the scale (9.2)which is commonly used, is loaded. The sliding valve (9.1) is closed andthe lower part of the valve is opened and the RDF is let into thegasifier. With the vacuum effect, the whole RDF is fed into the system.

In order to improve efficiency and to obtain higher quality gas, the RDFlevel in the gasifier (1) needs to be supervised by the operator andthis can be done thru ultrasonic voiced level indicator (12). In orderto control the RDF, there is an optional high heat and vacuum resistantwindow (12.1).

The sliding cover (12.2) used for protecting the inspection window isformed in a single sliding cover system and prevents the pollution ofthe inspection window by tar gases and explosions of gas in the gasifier(1). The sliding cover (12.2) is opened when there is high vacuum ingasifier (1) and thus it helps to extract the tar gases in the dryingzone (3). The inspection window (12.1) is located at the same place withthe level indicator.

The security valve (11) is used to prevent damage in the system for whenthere is a sudden pressure increase in the system and when there is gasaccumulation at the drying zone at the pyrolysis (4) and drying zones ofthe gasifier (1) and when the gas can not find a path to outflow fromthe system. The thermocouple (13.2) located in the drying zone is usedto transmit the heat information in this zone to the supervision room.

The pressure meter (14, 14.1, 14.2) in the drying zone is used to checkthe vacuum power applied by the fan (24). The pressure meter (14.1) usedduring downdraft mode indicates the pressure of the syngas outlet. Theother pressure meter (14.2) is used for the same purpose in the updraftmode.

The hydraulic piston (21) located in the drying zone is loweredoccasionally in order to break down the hard plastic formation withinthe gasifier (1). Failing to do so will cause the interruption of thesystem as it prevents the formation of vacuum.

The RDF after the drying zone moves into the pyrolysis zone (4) as it isseen in FIG. 1. The important portion of the gas is formed in thepyrolysis zone (4) . In other zones, the syngas is brought to itsdesired condition, cleaned and reducted for its further processing. Inup/downdraft working modes, this zone (4) is the oxygen free combustionzone. At the lack of oxygen the partial combustion reactions arerealized here. The vibrator (10) located in the pyrolysis zone vibrateswhen the RDF flow is not proper.

The thermocouple (13.1) is used to transmit the heat information in thepyrolysis zone (4) to the supervision room. The hazardous waste sprayingnozzles (20) are used to feed the hazardous waste into the gasifier (1).Sprayed liquid hazardous waste is completely mixed with the reactionsand increase the syngas efficiency within the pyrolysis zone (4). Theproportional valve (20.1) is used to feed the liquid hazardous wasteinto the gasifier in defined quantities.

The next zone within the gasifier where the gas is processed is theoxidation zone (5). Air nozzles (4.2), lower air nozzles (4.3) for thedowndraft working mode are located in the gasifier (1), and first airnozzles (4.3, 4.2) for downdraft mode and second air nozzles (4.5, 4.6)for updraft mode are activated. For the updraft mode, the upper airnozzles (4.5) are located in an angular manner to lower air nozzles(16). The distance between the two air nozzles are defined according tothe RDF properties and the ash quantity. The gap between the two airnozzles (4.2 and 4.3) forms the first oxidation zone (5). In this zonethe heat and the carbon monoxide formation is high. The air nozzles (4.2and 4.3) are made of high heat resistant high alloy stainless steellocated separately from each other and parallel to the gasifier bed (1)so that they do not get clogged. Not all air nozzles can be activated atthe same time.

For downdraft mode, the air chamber (4.7) is active whereas for updraftmode, the air chamber (4.8) is active.

Air entering from either (4.1) or from left or right air valves (6.2)can circulate through all of the nozzles (4.2, 4.3).

The air nozzle (4.4) located at the upper side of the pyrolysis zone(4)for the downdraft mode is designed and located there to fix the level atthe oxidation zone (5) and the pyrolysis zone (4).

This increases the speed of full combustion reactions by giving air oroxygen in a controlled manner to the complete surface of the oxidationzone (5). This optimizes partial combustion reactions in the pyrolysiszone (4). It is important to keep the RDF level not lower than the airnozzle (4.4). Unlike other air nozzles, via proportional valve (19), airor oxygen is introduced in a controlled manner thru the air nozzle(4.4).

The Bouduard reactions are realized in the reduction zone (6) of thegasifier during the downdraft working mode. Active carbon content highmaterials such as ash and tar are found. The reduction reactions arecompleted in this zone (6) for the syngas sucked from pyrolysis zone(4), tar gas and the carbon dioxide. The syngas, the gas mixture formedin pyrolysis zone (4) are directed to the reduction zone (6) andreducted when it is passing thru the tar and ash mixture.

The ash needs to be discharged during the catalytic cracking reactionswhen the tar quantity is lowered and the ash content is high. Ashdischarge timing is directly related to the retention time of the RDF inthe reduction zone (6). There is the thermocouple (13.3) to transmit theheat information from this zone to the supervision room.

The gasifier is positioned on a 50-70° angle to the ground so thatoxidized RDF in tar and ash form can easily flow downward to thereduction zone.

When the gasifier is running at updraft mode, the parts active at thereaction zone (6) are upper air nozzles (4.5), lower air nozzles (4.6),air chamber (4.8), lower preheated air or oxygen inlet (6.2),proportional valve (6.4) for air or oxygen inlet, ash grate (7.1) at thegas outlet zone for creating centrifugal effect, vapour nozzles (7.2)for increasing the carbon monoxide and hydrogen quantity to enrichsyngas, igniter (8.1), igniting system (10.1) for the arc formation,thermocouple (13.3), vapour proportional valve (15) to regulate vapourrate, refractory material inside the zone (7.4) to prevent heatdissolvement.

The air flow into the air chamber (4.8) is regulated via theproportional valve (6.4) for air or oxygen inlet into the gasifier (1)during the updraft working mode and the valve (17) is opened to createvacuum.

As the ash content in the reduction zone (6) increases, clogging mayoccur.

Vacuum disappears and sucking of gas is prevented, ash is discharged.

The ash formed in the reduction zone (6) follows the ash path (7.3) andis discharged to ash system (22) thru the ash carrier. The firstthreaded carrier (22.1) carries the big particulate ash from the watertrap into the dry ash pool (22.4). The second threaded carrier is usedto carry accumulated and suspended ash to the dry ash pool (22.4). Theash pallet (22.3) carries the bottom accumulating ash to the secondthreaded carrier (22.2). In order to decrease the ash content in the ashpool (22), dry ash pool that contains dehydrated ash.

The ash discharge system is trapped into the pool with water in order toprevent the air leakage into the reduction zone (6) since there isvacuum effect in the gasifier (1). The inner holes of the ash grate(7.1) located in the ash part of the reduction zone are made out of highalloy stainless steel and the syngas formed in and moving from thepyrolysis zone (4) passes thru it. This grate (7.1) has catalytic effecton reduction process to provide more effective and simpler reactions.The active carbon rich tar kept by the grate (7.1) provides smooth flowof the syngas and carbon dioxide mixture. During this flow the catalysiseffect of the grate takes place and both the carbon dioxide andmethanization reactions are completed. The particles carried by thesyngas formed in and carried from the pyrolysis zone (4) are dissolvedon the grate (7.1) due to the catalytic effect and the syngas isconveyed to have the catalytic cracking by passing through these grates(7.1) by a centrifugal effect.

Water gas reactions are realized via water vapour coming to thereduction zone (6) from three different sources. The first one of theseis thru the inlet of vapor nozzles (7.2) which introduces vapor to thesystem under control.

The second one of these vapor sources from the dehydrated RDF isintroduced in RDF form to the system and lets the water to evaporate inthe drying zone (3) and sucked into the reduction zone (6) by the vacuumeffect and creates water gas effects and this is considered as thevapour resource. The third one is through the controlled suction ofvapor from the ash pool at the ash discharge system thru the vacuum bycausing the water vapour phase balance impaired. Thus, the content ofhydrogen resulting from water gas reactions and carbon monoxideresulting from water gas coverage reactions increase. The vapourresulting from these three sources especially the one resulting from thevapour nozzles (7.2) complete the hydro cracking reactions since it issucked by the char in the carbonated ash after the pyrolytic process. Asa result of these hydro cracking reactions, the efficiency of pyrolyticreaction is increased. The hydrogen and carbon monoxide increases bypromoting the gas combination.

In order to stabilize reduction and water gas reactions in the lowerreduction zone (6), the vapor from vapor nozzles (7.2) are regulated.

The vapor nozzles (7.2) are only used during downdraft working mode byopening the valves (18) fully. In order to realize the water gasreactions, water vapor is introduced in a controlled manner viaproportional valve (15).

The gasifier is placed on a flexible wire (10.1) as a support in orderto prevent loose joints and deformations on the gasifier (1) when it isworking at high heat and vibration is applied. Thus, when the vibrationis applied, the complete reactor shakes and joints do not loosen.

The updraft and downdraft modes conducted in the present gasifier are asdescribed below. The parts which are common to both modes are asfollows:

RDF is weighed and passed thru the bottleneck (2). The RDF meets for thefirst time the heat in oxygen free environment in the bottleneck zone(2). The heat is appropriate for dehydrating the RDF that increaseshydrogen with gasification. The vacuum inside the gasifier provides safeworking conditions and the suction power of the fan (24) is justsufficient to provide gasification process continuity.

RDF after the bottleneck zone meets the oxygen free environment createdby vacuum in the drying zone (3). The oxygen and water free RDF getsready for the pyrolysis zone (4) in this zone by using the oxygencontent and by evaporating the water content.

Syngas pre-cooling and scrubbing unit (23) is also the same for bothmodes. Here, the outlet syngas from the gasifier is precooled andcleaned. Especially, use of the vapor exchanger creates the differencefrom conventional systems. The organic gases containing energy(CO—CH4—C2H4—C3H8) face sudden temperature decrease in scrubber and theyare let in water with tar, so the energy in the gas is highly lost.Without the vapor exchanger integration, it is not possible to protectthe syngas and to obtain an efficient gas after the scrubber. In orderto protect the energy of the gas, the heat is decreased in vaporexchanger without destroying the energy content in the organic gas. Theparticles are taken away without destroying the energy content in theorganic gases. The gas combination proceeds after scrubber once its tarand solid particles are removed.

UPDRAFT WORKING MODE

In this mode, since the vacuum will be upwards, the RDF needs to be fedby considering the operation safety. The vacuum range before and afterfeeding the RDF is the same. At updraft mode, the fan (24) operates on aless rate (2100 rpm) that is because the gas is not sucked from the ashbut thru the dry RDF in the pyrolysis zone (4).

Via the level indicator (12), the level of RDF is checked. When thesliding valve (12.2) under the inspection window is opened, theprojector and the inspection camera are automatically run. Theinformation is continuously transmitted to the supervision room.

The evaporated water in the drying zone (3) is sucked into the reductionzone by the vacuum and used for water gas reactions. The oxygen in theRDF is sucked by the vacuum to be used in the pyrolysis zone (4).

During updraft mode, since the gas will be passing thru the drying zone(3), the oxygen and the water content in RDF are depleted quite fast. Inthis working mode, the water gas reactions are realized more effectivelycompared to the downdraft mode and thus recovered hydrogen gas isincreased.

The particles and tar formed in the pyrolysis zone are not filtrated andnot reducted and that is how they are sucked because in updraft form,the syngas is not passing thru the ash and the feeding is realized inshorter period. Therefore less clean syngas is sucked from the systemcompared to the downdraft mode. The syngas zone (3.1) is activatedduring the updraft form. The valve (17) is opened for the updraft mode.The proportional valve (6.4) is opened and proportioned according to thefed material in order to create vacuum in the gasifier.

The gas continues upwards to the outlet (3.2) under vacuum. However,since the tar gas formed in the pyrolysis zone (4) is also sucked andthe syngas moves without being reducted. For the updraft mode, the zonewhich is 10 cm away from the oxidation zone lower air nozzles (4.5, 4.6)is the pyrolysis zone.

In order to switch from the downdraft working mode, the valves (18 and6.3) are fully closed. For starting up the updraft mode, igniters (8.1)are ignited and they are turned off after the ignition. For the updraftmode the igniters (8.1) are located at each air chamber (4.7 and 4.8).For this mode, igniters are located symmetrically to each other in airchamber (4.8). It is important to ignite them mutually at the oxidationzone during the start up.

During the updraft mode the upper syngas zone is active (3.2). The valve(17) is completely open in this zone. The proportional valve (6.4) isopened by the operator to create vacuum in the system. First oxidationzone is located in front of lower air nozzles (4.5, 4.6). The hot syngaspasses thru the air in oxidation zone (6.2) and that is how the air isheated and the syngas is cooled. The syngas is low quality in this modesince it contains more tar and this tar gas is not reducted.

The syngas desired to be recovered under vacuum condition defines theamount of the RDF to be fed and expected ash amount will vary accordingto the elements in RDF.

When carbon content high material is fed to the pyrolysis zone, theprocess slows down and ash/tar content increase. Therefore; materialfeeding should slow down and ash discharge should speed up. Whereas forthe hydrogen rich materials, the tar and ash formation is low and theRDF feeding should slowly increase and ash discharge should slowlydecrease.

In updraft mode, in the reduction zone (6), the air chamber (4.8) isused. The valve (17) is fully opened. The proportional valve (6.4) isproportionally opened for creating vacuum. It is the first chamber wherethe air is introduced into the gasifier (1). The air inlet is regulatedthrough the proportional valve (6.4). The air flows into the air chamber(4.8) under vacuum and from there it proceeds to the oxidation zone (5)to continue with the oxidation reactions.

The stainless steel slope is designed for preventing the excess heat upin the air chamber by meeting the cold air. When the hot syngas passesthru either oxygen or air inlet zone (6.2), the air coming in warms upand the syngas cools down. Only during the downdraft mode, vapor isintroduced to the reduction zone (6) thru the vapor nozzles (7.2) viaproportional valves (15). These valves (15) are fully closed during theupdraft mode and no vapor is introduced. There is no interruption duringthe switching between the downdraft and updraft modes.

During the switching between the modes, fan (24) is closed and thevalves are selectively opened according to the desired mode. Othervalves are closed. The fan (24) is then operated again and let thereactions continue without any interruptions.

DOWNDRAFT WORKING MODE

When downdraft mode is active under vacuum, the RDF flows downwardlythrough the bottleneck zone (2). Long chain hydrocarbons are cracked indrying zone (3) and transferred into monoxide form with the partialcombustion at the pyrolysis zone (4) and the combustible carbon monoxidegas is sucked by the vacuum. In the updraft mode, this tar-gas formed atthe pyrolysis zone is not reducted in ash form and is not filtratedthus, all the tar gas mixes up with syngas and lowers the quality.Therefore, in downdraft mode, the gas recovered is cleaner.

When the hot syngas is introduced from the preheated air or oxygeninlet, the air coming in is heated up and the syngas is cooled down.During the downdraft mode when the oxidation zone (5) is active, thevalve (18) is fully open and activated. During this mode, the lowersyngas outlet zone (6.1) is activated. The proportional valve (6.3) isopen to create vacuum within the gasifier. Oxidation zone is whereoxygenated combustion reactions are realized. There is high amount ofcarbon monoxide formation. Oxidized RDF starts up pyrolysis process.When the cycle starts, the RDF processed at the oxidation zone getslighter, flows downward and new RDF is fed once the ash discharged.

During the downdraft mode, the air within the gasifier (1) flows to theair chamber (4.7) under vacuum and from there it enters into theoxidation zone (5) and continues oxidation reactions. The lower airnozzles (4.6) are only used for updraft form.

The air chamber (4.7) is the part where air meets and the valve is open(19) in the downdraft mode. In the oxidation zone (5), air or oxygen isfed into the nozzles (4.4) in a controlled manner for the process to beproperly continued. The proportional valve is opened (6.3) for vacuumcreation. The required amount of air is introduced by valve (6.3). Theair comes into the air chamber (4.7) under vacuum and goes down to theoxidation zone (5) to continue reactions. The heat balance is created bycooling down the stainless steel slope by the cold air entering into theair chamber. The hot syngas passes thru the oxygen inlet (4.1) so theinlet air is heated up and outlet syngas is cooled down. These valvesare closed in updraft working mode (6.3).

While working in downdraft mode, the water vapor is not introduced atthe first stage. Once the gasifier reaches its ideal temperature, inorder to improve the quality of the outlet syngas, the syngas analysisis made and vapor is introduced into the system in a controlled manner.The vapor is at 150-170° C. when introduced into the reduction zone (6)only thru symmetrical nozzles (7.2) via proportional valve (15). Duringthe updraft form, these valves (15) are fully closed and there is novapor introduction.

At the updraft mode, the RDF is easily fed into the bottleneck zone (2)thru the vacuum formed by the fan (24). The ideal form of the RDF isquickly obtained by sucking the oxygen and water in RDF under heat andvacuum conditions at the drying zone (3).

The vacuum facilitates the oxidation reactions to be completedsuccessfully and the flow of the RDF within the gasifier (1).

The syngas compound sucked from pyrolysis zone (4) and the flow of tarpasses through the gas reduction zone (6) and grate (7.10) undercentrifugal effect created via vacuum. Centrifugal reduction of the gasrecovers cleaner gas.

During the ash discharge from the gasifier (1), the fan (24) intervenesinto the water phase balance in the ash pool. The vapor generated due tothe water phase destruction, flows into the ash discharge line (7.3) andreaches to the reduction zone (6) and there promotes water gasreactions.

During the downdraft working mode, the valve (18) is fully open and theproportional valve (6.3) is proportionally open to create vacuum. Inorder to switch from updraft mode, the valves (17 and 6.4) are fullyclosed.

In order to start the downdraft mode, the igniters (8) are activated andthey are turned off after ignition. For this mode, the igniters (8) arelocated in each air chamber (4.7 and 4.8). Once the process starts, theyare deactivated. The igniters are positioned symmetrically in the airchamber (4.7). The igniters are fed thru the LPG system. The end pointof igniters are located in between the air nozzles (4.2 and 4.3). It isimportant to ignite the igniters mutually on the oxidation zonesimultaneously. There is no continuous LPG feeding.

Although the invention is explained in respect to the above embodimentsand methods, various modifications are evident for the persons skilledin the art without departing from the essence of the invention asdefined in the attached claims.

1. A gasifier (1) which permits the switching between downdraft andupdraft modes without any interruption during the gasification processaccording to the feedstock material and the gas produced, comprising ascale (9.2), a bottleneck zone (2) that comprises a double sliding valve(9) and a rotating valve (9.1) where the waste is exposed to heat forthe first time in oxygen free environment; a drying zone (3.1) locatedunder the bottleneck zone (2) with a diameter bigger than the bottleneckzone comprising a higher syngas outlet zone (3.2), a safety valve (11),a level indicator (12), an inspection glass (12.1), a sliding cover(12.2), a thermocouple (13.2), a pressure forwarder (14), a pressuremeter in syngas outlet zone, a proportional valve (19) and a hydraulicpiston (21); a pyrolysis zone (4) located under the drying zone (3)comprising a preheated air and oxygen inlet (4.1), air nozzles (4.4), avibrator (10), a thermocouple (13.1), liquid hazardous waste injectionnozzles (20), a proportional valve for hazardous liquid waste (20.1); acambered oxidation zone (5) comprising top air nozzles (4.2), bottom airnozzles (4.3), an air chamber (4.7), a bottom syngas outlet zone (6.1),proportional valve for air and oxygen inlet (6.3), igniters (8), atemperature meter in first oxidation zone (13), a pressure meter (14.1)at the syngas outlet zone; a reduction zone (6) interior surface ofwhich is covered with refractory material to prevent heat dissolvementcomprising upper air nozzles (4.5), lower air nozzles (4.6), an airchamber (4.8), lower preheated air or oxygen inlet (6.2), proportionalvalve (6.4) for air or oxygen inlet, an ash grate (7.1) at the gasoutlet zone for creating centrifugal effect, vapour nozzles (7.2) forincreasing the carbon monoxide and hydrogen amount to enrich syngas, anigniter (8.1), igniting system (10.1) for the arc formation, athermocouple (13.3), a vapour proportional valve (15) for regulating thevapour percentage; an ash section (7) comprising ash discharger (7.3),an ash pool (22), a first threaded carrier (22.1) to convey bigparticles from ash discharger into the ash pool, a second threadedcarrier (22.2), an ash carrying palette (22.3); a precooler and scrubbersystem (23) placed between the gasifier reactor and fan and comprising acyclone, syngas vapor exchanger, a gas cleaning scrubber and an electrostatic precipitator at least one fan (24) and valves (17, 18).
 2. Thegasifier as claimed in claim 1 wherein the inner surface of which iscompletely or partially coated with refractory material.
 3. The gasifieras claimed in claim 1 characterized in that precooling and scrubbingsystem (23) comprises a vapor exchanger.
 4. The gasifier (1) as claimedin claim 1 characterized in that the stainless steel oxidation zone iscambered.
 5. The gasifier (1) as claimed in claim 1 characterized inthat said ash zone (7) comprises at least one ash discharger (7.3), atleast one ash pool (22), a first ash carrier (22.1) that carries bigparticles from ash discharge into the ash pool, at least one secondthreaded carrier (22.2), at least one ash carrying palette (22.3) and atleast one dry ash pool (22.4).
 6. The gasifier (1) as claimed in claim 1characterized in that the said second threaded ash carrier (22.2) isprovided to carry the accumulated ash at the bottom and small particlesfloating in the dry ash pool (22.4) via ash carrying pallet (22.3). 7.The gasifier (1) as claimed in claim 1 characterized in that the saidfirst threaded ash carrier (22.2) is located with an angle of 30-45° tothe ground.
 8. The gasifier (1) as claimed in claim 1 characterized inthat gasifier provides the syngas compound formed in and arriving fromsaid pyrolysis zone (4) to carry particles that dissolve on the grate(7.1) and causes the catalytic cracking of the syngas while passingthrough the grate (7.1) with centrifugal effect.
 9. The gasifier (1) asclaimed in claim 1 characterized in that said igniters (8.1) are locatedon air chambers (4.7 and 4.8) of the gasifier.
 10. A gasifying methodrealized in the gasifier as claimed in claim 1 comprising the steps of:a) transmitting the RDF from the bottleneck zone (2) after beingweighed; b) closing valves (17 and 6.4) and opening valves (18 and 6.3);c) activating igniters (8) and then deactivating them once gasificationstarts; d) exposing RDF to heat in an oxygen free environment at thebottleneck zone (2); e) dehydrating RDF at the drying zone (3) in anoxygen free environment under vacuum; f) sucking water obtained at step(c) above into the reduction zone (6) under vacuum; g) sucking oxygenobtained at step (c) into the pyrolysis zone (4) under vacuum; h)opening valve (18); i) opening the proportional valve (6.3) according tothe RDF quantity that is being processed; j) moving of the gas todownwardly towards the outlet (6.1); k) introducing water vapor into thereduction zone (6) through the vapor nozzles (7.2) via proportionalvalves (15) while working in downdraft mode.
 11. An updraft gasifyingmethod realized in the gasifier as claimed in claim 1 comprising thesteps of: a) transmitting the RDF from the bottleneck zone (2) afterbeing weighed; b) closing valves (18 and 6.3) and opening valves (17 and6.4); c) activating igniters (8.1) and then deactivating them oncegasification starts; d) exposing RDF to heat in an oxygen freeenvironment at the bottleneck zone (2); e) dehydrating RDF at the dryingzone (3) in an vacuum oxygen free environment under vacuum; f) suckingwater obtained at step (c) above into the reduction zone (6) under g)sucking oxygen obtained at step (c) into the pyrolysis zone (4) undervacuum; h) opening valve (17); i) activating the syngas zone (3.1); j)opening the proportional valve (6.4) according to the RDF quantity thatis being processed; k) moving of the gas to downwardly towards theoutlet (3.2);
 12. The method as claimed in claim 10 characterized inthat the amount of RDF to be processed is adjusted to the discharged ashquantity.
 13. The method as claimed in claim 10 characterized in thathot syngas is passed through air or oxygen inlet (6.2) to heat theincoming air.
 14. The method as claimed in claim 10 characterized inthat water vapor is introduced into the reduction zone (6) through vapornozzles (7.2) via proportional valves (15).
 15. The method as claimed inclaim 11 characterized in that in updraft mode said proportional valves(15) are closed and vapor passage is prevented.
 16. The method asclaimed in claims 7 to 10 characterized in that said the fan (24) isclosed during the switching between updraft and downdraft modes.
 17. Themethod as claimed in claim 10 characterized in that water vapor isintroduced into reduction zone (6) thru (7.1) in a controlled manner.18. The method as claimed in claim 10 characterized in that water vaporis introduced into the reduction zone (6) via two nozzles (7.2) that aresymmetrically positioned to each other.
 19. The method as claimed inclaims 10 and 11 characterized in that water vapor formed out ofwater/vapor phase destruction caused by the said fan (24) during thesuction of water from the gasifier moves in the ash discharge line (7.3)towards the reduction zone (6) under vacuum.
 20. The method as claimedin claim 10 characterized in that said igniters (8) are closed once theignition is completed.
 21. The method as claimed in claim 10characterized in that said igniters (8) are mutually and simultaneouslyignited at the first oxidation zone.